Vandergrift is a borough in Westmoreland County, Pennsylvania, United States, approximately 40 miles (64 km) east of Pittsburgh. Early in the 20th century, it had the largest sheet steel mill in the world. In July 1915, the borough of Vandergrift Heights was consolidated with Vandergrift. In 1900, 2,076 people lived here; in 1910, 3,876. The 1915 consolidation almost doubled the Vandergrift population when Vandergrift Heights added approximately 3,438 new residents (1910 population). By 1940, 10,725 people lived in Vandergrift. The population was 5,455 at the 2000 census, and 5,205 in 2010. Many of the exterior shots in the 2011 science-fiction film "I Am Number Four" were filmed in Vandergrift, which was a stand-in for the fictional town of Paradise, Ohio.
In the 1890s the Apollo Iron and Steel Company ended a bitterly contested labor dispute by hiring replacement workers from the surrounding countryside. To avoid future unrest, however, the company sought to gain tighter control over its workers not only at the factory but also in their homes. Drawing upon a philosophy of reform movements in Europe and the United States, the firm decided that providing workers with good housing and a good urban environment would make them more loyal and productive. In 1895, Apollo Iron and Steel built a new, integrated, non-unionized steelworks and hired the nation's preeminent landscape architectural firm, Olmsted, Olmsted and Eliot, to design the model industrial town: Vandergrift.